Passive millimeter wave spectrometer for remote detection of chemical plumes

Abstract

Systems and methods for the passive measurement of spectral lines from the absorption or emission by polar molecules. The system includes mmW front-end assembly, back-end electronics, and data acquisition hardware and software was assembled. The method relates to methods for processing multi-channel radiometric data from passive mmW detection systems.

1. An apparatus for remote detection of chemicals, comprising:
 front end unit comprising a receiver, and an optical chopper; 
 a back end unit comprising an amplifier; and 
 a data acquisition and analysis module; 
 
       wherein the front end unit detects millimeter waves and separates millimeter wave associated with a background from the millimeter wave associated with a foreground using the optical chopper, the receiver transmitting a signal representative of the detected millimeter waves for pre-processing and amplification by the back end unit which transmits the signal to the data acquisition module for post-processing and detection of the chemicals. 
     
     
       2. The apparatus of  claim 1  wherein post processing is performed by at least one component selected from the group consisting of a component for amplitude normalization, frequency domain scene subtraction, time domain integration, time domain baseline subtraction, channel stacking, and combinations thereof. 
     
     
       3. The apparatus of  claim 1  wherein the receiver comprises a superheterodyne receiver which converts the millimeter waves to intermediary frequency range waves. 
     
     
       4. The apparatus of  claim 3  wherein the back end unit includes a component which amplifies the intermediary frequency waves and splits the signal into a plurality of channels. 
     
     
       5. The apparatus of  claim 4  wherein the signal includes a component for separation into four channels of data. 
     
     
       6. The apparatus of  claim 5  wherein each of the four split channels of data is further split into four channels forming sixteen channels of data. 
     
     
       7. The apparatus of claim l wherein the receiver includes a component which functions in a Dickie-switched mode. 
     
     
       8. The apparatus of claim l wherein the data acquisition and analysis module comprises a computer system. 
     
     
       9. The apparatus of  claim 8  wherein the computer system comprises computer program code for graphical display of a millimeter wave profile.